Abstract: A method for controlling operation of a transfer case clutch in a motor vehicle driveline controlled by an engine throttle having a variable position. The transfer case transmits rotating power to a primary power path and to a secondary power path in response to an electric current duty cycle applied to a coil that actuates the clutch. The method includes the steps of determining that a current vehicle speed is less than a reference vehicle speed; determining that the engine throttle position is in a reference throttle position range; determining that a change in vehicle speed is greater than a reference change in vehicle speed; using a current magnitude of torque in the driveline to determine a desired duty cycle for the coil; and applying a duty cycle of the desired magnitude to the coil.

Abstract: A four wheel drive powertrain control for an automotive vehicle is disclosed. It includes a torque transfer case that distributes power from an engine-powered transfer case mainshaft to a secondary driving axle through a friction clutch as power is distributed directly from the engine-powered mainshaft to a primary driving axle. The friction clutch capacity is sufficient to mechanically lock the transfer case in a four wheel drive mode. If the clutch torque capacity is exceeded, a control algorithm will strategically ramp down engine torque requests by a powertrain controller to eliminate clutch slip.

Abstract: A method for controlling operation of a transfer case clutch in a motor vehicle driveline controlled by an engine throttle having a variable position. The transfer case transmits rotating power to a primary power path and to a secondary power path in response to an electric current duty cycle applied to a coil that actuates the clutch. The method includes the steps of determining that a current vehicle speed is less than a reference vehicle speed; determining that the engine throttle position is in a reference throttle position range; determining that a change in vehicle speed is greater than a reference change in vehicle speed; using a current magnitude of torque in the driveline to determine a desired duty cycle for the coil; and applying a duty cycle of the desired magnitude to the coil.

Abstract: A four wheel drive powertrain control for an automotive vehicle is disclosed. It includes a torque transfer case that distributes power from an engine-powered transfer case mainshaft to a secondary driving axle through a friction clutch as power is distributed directly from the engine-powered mainshaft to a primary driving axle. The friction clutch capacity is sufficient to mechanically lock the transfer case in a four wheel drive mode. If the clutch torque capacity is exceeded, a control algorithm will strategically ramp down engine torque requests by a powertrain controller to eliminate clutch slip.

Abstract: A transfer case control system or apparatus 10 is provided for use on a four-wheel drive vehicle of the type having a transfer case 32, a front driveshaft 22 and a rear driveshaft 26. Transfer case control system 10 includes a conventional microcontroller or controller 40 having a memory unit 42 and operating under stored program control. Controller 40 is communicatively coupled to sensors 44, 46, 48, and to transfer case 32. Controller 40 selectively transmits a torque control or “boost torque” signal to transfer case 32, based upon the rate of change of the vehicle's throttle position and the speed of driveshafts 22, 26.

Abstract: A transfer case control system or apparatus 10 is provided for use on a four-wheel drive vehicle of the type having a transfer case 32, a front driveshaft 22 and a rear driveshaft 26. Transfer case control system 10 includes a conventional microcontroller or controller 40 having a memory unit 42 and operating under stored program control. Controller 40 is communicatively coupled to sensors 44, 46, 48, and to a transfer case 32. Controller 40 selectively generates a control signal having a proportional term or component and an integral term or component. The control signal is generated to transfer case 32 and controls the amount of torque provided to driveshafts 22, 26.

Abstract: A transfer case control system or apparatus 10 is provided for use on a four-wheel drive vehicle of the type having a transfer case 32, a front driveshaft 22 and a rear driveshaft 26. Transfer case control system 10 includes a conventional microcontroller or controller 40 having a memory unit 42 and operating under stored program control. Controller 40 is communicatively coupled to sensors 44, 46, 48, and to transfer case 32. Controller 40 selectively transmits a torque control or minimum duty cycle signal to transfer case 32, which is at least partially based upon the angular position of the vehicle's steering wheel and the speed of driveshafts 22, 26.

Abstract: A system 10 for controlling a transfer case clutch assembly is provided and is deployed within a four-wheel drive vehicle having a front driveshaft 22, a rear driveshaft 26, and a transfer case 32 which selectively provides torque to the driveshafts 22, 26 by way of a clutch assembly 38. System 10 includes a controller 40 which is communicatively coupled to the clutch assembly 38. Controller 40 receives signals generated by sensors 44-48, utilizes the received signals to determine the onset of a slip condition, and based upon this determination, generates a command signal to selectively activate the clutch assembly 38 effective to smoothly release torque from the front driveshaft 22 and/or rear driveshaft 26.

Abstract: A transfer case control system or apparatus 10 is provided for use on a four-wheel drive vehicle of the type having a transfer case 32, a front driveshaft 22 and a rear driveshaft 26. Transfer case control system 10 includes a conventional microcontroller or controller 40 having a memory unit 42 and operating under stored program control. Controller 40 is communicatively coupled to sensors 44, 46, 48, and to transfer case 32. Controller 40 selectively transmits a torque control or “boost torque” signal to transfer case 32, based upon the rate of change of the vehicle's throttle position and the speed of driveshafts 22, 26.

Abstract: A transfer case control system or apparatus 10 is provided for use on a four-wheel drive vehicle of the type having a transfer case 32, a front driveshaft 22 and a rear driveshaft 26. Transfer case control system 10 includes a conventional microcontroller or controller 40 having a memory unit 42 and operating under stored program control. Controller 40 selectively generates a control signal which controls the amount of torque provided to driveshafts 22, 26. Controller 40 provides an improved torque adjustment “response” by automatically adjusting to the condition of the vehicle's tires.

Abstract: A four-wheel drive system for a motor vehicle includes a transfer case through which power is continually transmitted to a first drive wheel pair and a clutch that controls a magnitude of torque transmitted to a second drive wheel pair in accordance with an electric current duty cycle applied to the clutch by a control unit that produces an output duty cycle in response to a range selected by the operator, the vehicle speed, and the position of the throttle that controls a power source driveably connected to the input side of the transfer case.

Abstract: A method of monitoring the relative effective diameters of the tires and compensating therefor in a vehicle which includes a front driveshaft for transferring motive power to a front set of wheels and a rear driveshaft for transferring motive power to a rear set of wheels, each of the wheels having an effective diameter. Front and rear driveshaft values indicative of the rotational speed of each driveshaft are generated. A difference value indicative of a difference between said front and rear driveshaft values is then generated. A low pass filtered value is generated according to the relationship of Y.sub.1p =(1-.beta.)*U(k)+.beta.*Y.sub.1p (k-1). The low pass filtered value is monitored for a predetermined period of time to determine if one of the wheels has a smaller effective diameter than the other wheels.

Abstract: In a vehicle which includes a front driveshaft for transferring motive power to a front set of wheels and a rear driveshaft for transferring motive power to a rear set of wheels and a clutch to control the amount of torque provided to the driveshafts, a method is provided to control the amount of power delivered to the front and rear driveshafts. The duty cycle of the clutch is monitored and it is determined whether the clutch duty cycle passes a first lower threshold and a second higher threshold, successively, a predetermined number of times within a calibratible time period. A 4 Hi Lock mode is entered if the clutch duty cycle passes the first lower threshold and the second higher threshold, successively, a predetermined number of times within the calibratible period.

Abstract: A method of controlling the amount of power delivered to the front driveshaft and to the rear driveshaft of a motor vehicle including the steps of generating a front driveshaft value indicative of the rotational speed of said front driveshaft and generating a rear driveshaft value indicative of the rotational speed of said rear driveshaft. A vehicle speed is generated based on the lower of said front driveshaft value and said rear driveshaft value. The amount of power delivered to said front driveshaft and to said rear driveshaft is controlled as a function of said vehicle speed.

Abstract: A circuit for correcting a fault in an automotive system having at least two operating states includes an actuator mechanism for placing the system into one of at least two operating states and a switching mechanism, such as a relay, operatively connected with the actuator mechanism for driving the actuator mechanism upon passing a current through the switching mechanism. The circuit further includes a fault warning mechanism for detecting an inability of the actuator to place the system into a desired operating state and for generating a fault warning signal in response to the detection as well as a control unit for activating the switching mechanism according to a predetermined sequence upon generation of the fault warning signal to correct the inability of the actuator mechanism to place the system into a desired operating state.

Abstract: A sensor for determining the operational position of an automotive suspension including two members relatively movable with respect to one another includes an assembly with the first component movable with respect to a second component, with the first and second components being relatively movable with respect to each other as a result of the movement of the vehicle suspension. A sensor according to this invention will further include, without limitation, a signal generation device associated with said first and second sensor components for generating a plurality of position signals including both unique and non-unique signals.

Abstract: A system for measuring ride height and relative vertical velocity of a motor vehicle suspension includes a sensor for detecting vertical motion of a wheel and tire assembly which is relatively movable with respect to the chassis of the motor vehicle and a processor operatively connected with the sensor for calculating the relative velocity of the suspension with respect to the chassis. The processor includes a mechanism for comparing the magnitude of the calculated velocity of the road wheel with a set of threshold velocity values and output circuits for producing a control signal in the event that the calculated velocity lies between two of the threshold values. The system also includes an adjustment mechanism operatively connected with the processor and responsive to control signals therefrom for adjusting an adjustable suspension unit.